It was the second attack on Christian missionaries in Lebanon in six months, and the most recent in a string of attacks on Western targets that has picked up pace since the U.S.-led invasion of Iraq. Security officials identified the dead man as a Jordanian acquaintance of the couple who had converted to Christianity, and said he had picked up the explosive device after it was spotted near the entrance to their apartment. "He examined it, saw a fuse and attempted to stop it," a security official said, "but it continued and the explosive went off." No one else was seriously hurt, security officials said. Witnesses said police cordoned off the neighborhood after the blast at around midnight, and detained at least three people for questioning. Security sources said their investigation, and interrogation of the detainees, was continuing on Wednesday afternoon, as security patrols combed the area. In November a gunman shot and killed an American missionary in the southern port of Sidon after Islamic militants warned her church against trying to convert Muslims to Christianity. The attack in Sidon, home to several Sunni Muslim militant groups, was the first killing of a Westerner in Lebanon since its 1975-1990 civil war, when Muslim extremists kidnapped and killed Americans and other Westerners. Security sources could not immediately identify a motive for the blast in Tripoli, also a center of Sunni Muslim militancy. But anti-Western feeling has risen in Lebanon during a 31-month-old Palestinian uprising against Israeli occupation and over the U.S.-led war in Iraq. A string of blasts have hit Western fast food outlets in Lebanon over the past year, and the U.S. embassy recently warned Americans to consider leaving Lebanon.